Re: [Amforth-devel] Progress and More Difficulties with Hello World exercise

[Kalus M. <mic...@on...>]

Hi.


Am 29.03.2011 um 21:33 schrieb Matthias Trute:
..
> Receiving characters is a completly different thing. The characters
> can come at any time, therefore the code needs to deal with the
> situation relativly fast (at least before the next character
> arrives).

If you just want to connect a terminal to type in commands, amforth  
is fast enough to handle this situation: Wait for a key, grab it, put  
it in inputbuffer, wait again.
amforths accepts keys till end of line, then interprets the line.
See: uart-rx-poll.asm
Since you - the user - wait for the ok of amforth to appear, there is  
no overflow.
I use 12Mhz chrystal, 14400 Baud, atmega168, works fine this way.

But to download a file you have to make shure your sending program  
will immediatly stop sending if a CR is echoed, and continues after  
OK is encounterd. Terminals usualy can not handle this situation.  
That is why Mathias is using a Phyton script for downloads.

I use ZTerm with Mac OSX. In typing mode, it stops sending when XOFF  
character is echoed, and continues after XON. So my amforth CR sends  
xoff to the Terminal too, and the OK is followed by XON.
(Typing mode: copy&paste forth souce into ZTerm window, do not use  
ZTerms file transfer feature. Setup the ZTerm as VT100 with line  
prompt character ^C ($13 = xoff)).

There may be about two characters on its way down to amforth till  
terminal finaly stops sending more characters. I allways insert 4 or  
more blanks at the beginning of each line in my forth sources to  
handle this situation. This way interpretation of a line stays  
successful even if some characters are lost in the handshaking process.

     : hallo ." hallo world" ;
^^^^

Maybe this helps.
Michael